A cancer-stricken groundskeeper has accepted a slashed award in a landmark trial focused on weed-killer Roundup, setting the stage for an appeal by maker Monsanto.

Judge Suzanne Bolanos last week denied Monsanto's request for a new trial but cut the $289 million damages award to $78 million to comply with the law regarding how punitive damages awards must be calculated.

In her ruling, Bolanos gave Johnson the choice of accepting the lessened damages award or triggering a new trial focused on what Monsanto should pay in the case.

An October 26 notice of acceptance of the judge's decision was filed on Johnson's behalf.

"However, to hopefully achieve a final resolution within his lifetime, Mr. Johnson has accepted the punitive damages reduction suggested by Judge Bolanos."

In her ruling, Bolanos denied a request by Monsanto to toss out the jury's overall verdict against the company.

Jurors in August unanimously found that Monsanto acted with "malice" and that its weed killers Roundup and the professional grade version RangerPro contributed "substantially" to Johnson's terminal illness.

The jury ordered Monsanto to pay $250 million in punitive damages along with compensatory damages and other costs, bringing the total figure to nearly $290 million.

Johnson, a California groundskeeper diagnosed in 2014 with non-Hodgkin's lymphoma -- a cancer that affects white blood cells -- says he repeatedly used a professional form of Roundup while working at a school in Benicia, California.

Monsanto-parent Bayer has vowed to appeal the case.

"The court's decision to reduce the punitive damage award by more than $200 million is a step in the right direction," Bayer said in response to an AFP inquiry at the time of the judge's ruling.

"But we continue to believe that the liability verdict and damage awards are not supported by the evidence at trial or the law and plan to file an appeal with the California Court of Appeal."

Monsanto attorney George Lombardi argued in court earlier this month that the evidence presented at trial did not sufficiently back the verdict, and that an attorney for Johnson was wrong to urge jurors to teach the company a lesson.

More to come?

Johnson's lawsuit built on 2015 findings by the International Agency for Research on Cancer, part of the UN World Health Organization, which classified Roundup's main ingredient glyphosate as a probable carcinogen, causing the state of California to follow suit.

Monsanto has defended the weed killer, arguing that it has a history of safe use that dates back more than 40 years.

The lawsuit is the first to accuse the product of causing cancer, but observers say a Monsanto defeat likely opens the door to thousands of other claims against the company, which was recently acquired by Germany's Bayer.

Roundup is Monsanto's leading product.

Despite its denials of any links between its products and ill health effects, Monsanto has already suffered hits to its reputation in light of the controversy.

Records unsealed earlier this year by a federal court lent credence to Johnson's claims -- internal company emails with regulators suggested Monsanto had ghostwritten research later attributed to academics.

Founded in 1901 in St Louis, Missouri, Monsanto began producing agrochemicals in the 1940s. It was acquired by Bayer for more than $62 billion in June.

Monsanto launched Roundup in 1976 and soon thereafter began genetically modifying plants, making some resistant to Roundup.